Elimination of the yellow pigment gene PSY-E2 tightly linked to the Fusarium head blight resistance gene Fhb7 from Thinopyrum ponticum

Authors: LI, XUEFENG - Shandong Agricultural University; LI, DONG - Shandong Agricultural University; XUAN, YU - Shandong Agricultural University; HE, ZIMING - Nanjing Agricultural University; ZHAO, LANFEI - Kansas State University; HAO, YONGCHAO - Shandong Agricultural University; GE, WENYANG - Shandong Agricultural University; XU, SHOUSHEN - Shandong Agricultural University; HOU, BINGQIAN - Shandong Agricultural University; WANG, BIAO - Shandong Agricultural University; GUO, JUN - Shandong Academy Of Agricultural Sciences; LIU, WENWEN - Shandong Agricultural University; LI, MINGZHU - Shandong Agricultural University; HAN, YI - Shandong Agricultural University; BO, CUNYAO - Shandong Agricultural University; BAO, YINGUANG - Shandong Agricultural University; QI, ZENGJUN - Nanjing Agricultural University; Xu, Steven; Bai, Guihua; WANG, HONGWEI - Shandong Agricultural University; KONG, LINGRANG - Shandong Agricultural University

Submitted to: The Crop Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/25/2022
Publication Date: 1/20/2023
Citation: Li, X., Li, D., Xuan, Y., He, Z., Zhao, L., Hao, Y., Ge, W., Xu, S., Hou, B., Wang, B., Guo, J., Liu, W., Li, M., Han, Y., Bo, C., Bao, Y., Qi, Z., Xu, S.S., Bai, G., Wang, H., Kong, L. 2023. Elimination of the yellow pigment gene PSY-E2 tightly linked to the Fusarium head blight resistance gene Fhb7 from Thinopyrum ponticum. The Crop Journal. 11(3):957-962. https://doi.org/10.1016/j.cj.2022.12.005.
DOI: https://doi.org/10.1016/j.cj.2022.12.005

Interpretive Summary: Fusarium head blight (FHB) and Fusarium crown rot (FCR), caused by Fusarium species, are two major fungal diseases in wheat. The gene Fhb7, originally transferred from tall wheatgrass (Thinopyrum ponticum) into bread wheat, is a major gene for resistance to FHB and FCR. However, Fhb7 on the wheatgrass chromosome segment is tightly linked with a gene PSY-E2 for biosynthesis of a pigment that produces yellow kernels and flour. Because yellow kernels and flour are an undesirable trait in bread wheat, Fhb7 cannot be used in wheat breeding. In this study, we successfully eliminated the yellow pigment gene PSY-E2 from Fhb7 using molecular marker-assisted chromosome engineering. The Fhb7 on the reduced wheatgrass chromosome segment without the yellow pigment gene was then deployed into three commercial wheat varieties. The resultant wheat lines carrying Fhb7 alone had enhanced FHB and FCR resistance and white kernels and flour, but without yield penalty. The new wheat lines carrying Fhb7 and molecular markers developed in this study are new resources for wheat breeders to efficiently deploy Fhb7 for controlling FHB and FCR in bread wheat production worldwide.

Technical Abstract: Fhb7 is a major gene that was transferred from Thinopyrum ponticum to chromosome 7D of wheat (Triticum aestivum) and confers resistance to both Fusarium head blight (FHB) and Fusarium crown rot (FCR). However, Fhb7 is tightly linked to the PSY-E2 gene, which causes yellow flour, limiting its application in breeding. To break this linkage, marker K-PSY was developed for tagging PSY-E2 and used with Fhb7 markers to identify recombination between the two genes. Screening 21,000 BC1F2 backcross progeny (Chinese Spring ph1bph1b*2/SDAU 2028) revealed two Fhb7+ wheat-Tp7el2L lines, Shannong 2–16 and Shannong 16–1, that carry a desired truncated Fhb7+ translocation segment without PSY-E2. The two lines show levels of resistance to FHB and FCR similar to those of the original translocation line SDAU 2028, but have white flour. To facilitate Fhb7 use in wheat breeding, STS markers were developed and used to isolate Fhb7 on a truncated Tp7el2 translocation segment. Near-isogenic lines carrying the Fhb7+ segment were generated in the backgrounds of three commercial cultivars, and Fhb7+ lines showed increased FHB and FCR resistance without yield penalty. The breakage of the tight linkage between Fhb7 and PSY-E2 via homoeologous recombination provides genetic resources for improvement of wheat resistance to FHB and FCR and permit the large-scale deployment of Fhb7 in breeding using marker-assisted selection.